3 i 4 THE IMPROVEMENT OF RIVERS. 



The top courses of the upper and lower miter-walls on the down-stream side of the 

 sills, and the top courses of tin- UPJKT and lo\\vr coffer-walls, shall be of special stone, as 

 directed in paragraph (e). These stones shall be pointed-face, with checks cut for the 

 sills, and snux>th chiseled. 



The river face of tin- river-wall, beginning at a point 2 feet below the lower pool level, 

 tin- lower ends of both main walls, and the exposed face of the lower wing-wall, Ix'ginning 

 at the same level, and the upper ends of both main walls, and the exposed face of the 

 upper wing-wall, beginning at a point 2 feet below the upper pool level, shall be faced 

 with rock-face stone. That portion of the river wall against which the dam is to abut 

 shall be picked off to the satisfaction of the Engineer without extra cost to the United 

 States. 



The inside of the culverts, except where special stone is to be used, shall be of rock- 

 face stone. 



(/) Dressing, etc. The beds of all stone must be their natural quarry-beds. All 

 stone must be shaped up before being brought on the walls, and the style of face-dress- 

 ing must be uniform for all stones of similar finish. The edges of cut stone must be truly 

 and sharply finished, and no stone of this class with chipped edges will be accepted. 

 No lewis holes, dog holes, letters, or other disfigurements will be permitted on any 

 face visible in the finished work. No stone finished by machinery will be permitted 

 on any exposed face. 



(m) Laying Masonry. Before setting any stone the stone itself and its site shall 

 be thoroughly wetted and scrubbed clean. Every stone shall be well laid to proper 

 lines' and in full beds of mortar, and be set with heavy wooden mauls, and must proj>erlv 

 bond and break joints with the adjacent pieces. The bond of any stone shall in no case 

 be less than 9 inches. The spaces between the joints of backing stone shall nowhere 

 exceed 8 inches, and must within these limits be as small as the stone will allow. These 

 spaces shall be filled with mortar, into which wet spalls must be well rammed in layers; 

 the spalls must not be put in first. Backing shall not be laid in advance of face stone, 

 and face stone must be promptly and thoroughly backed. No face stone shall be set 

 until the stone below it has been thoroughly backed. 



Not more than 3 unfinished courses will be allowed on any wall without per- 

 mission of the Engineer. 



No stone shall be dressed or hammered without permission after having been set 

 in the wall. Any stone chipped or spalled after having been set shall be removed and 

 replaced at the contractor's expense, or shall be paid for at a cheaper classification, 

 at the option of the Engineer. Stones having defects purposely concealed will be 

 rejected, whether set or not. 



No joints in face stone will be allowed above or below a header. 



() Special Dimension Stone. The contractor, if so required by the Engineer, must 

 get out additional stone to special dimensions and drawings, the finish of each stone 

 to determine its classification and payment, as hereinbefore specified. 



